1. Field of Invention
The present invention relates generally to the field of oilfield exploration, production, and testing, and more specifically to swellable elastomeric materials comprising nanoscale materials and their uses in such ventures.
2. Related Art
Recently there has been a growing interest in swellable elastomers for use in oilfield applications. Oil-swellable packers are now on the market, as well as expandable zonal isolation profilers that use a water-swellable elastomer. There are reported to be water-swellable and oil-swellable packers on the market for oilfield applications, although it is not known if these packers swell in both oil and water. Other oilfield elements and tools may utilize swellable elastomers, for example, swellable elastomers and other polymers may be used in blow out preventer elements.
Nanocomposites are a relatively new class of composites that are particle-filled polymers for which at least one dimension of the dispersed particle is in the nanometer range (10−9 meter). Because of the size of the dispersed particles, certain nanocomposites may exhibit improved mechanical, thermal, optical, and electrical properties as compared to pure polymers or conventional composites.
U.S. Pub. Pat. App. No. 20020117659 discloses nanowires and nanoscale devices and more particularly a nanoscale device having a nanowire or functionalized nanowires for detecting the presence or absence of an analyte suspected to be present in a sample, and methods for using same. U.S. Pat. No. 6,705,152 discloses sensors comprising micromachined anodic aluminum oxide films which contain an extremely high density of nanoscale pores (e.g., 1011 cm−2). Sensing materials deposited inside this self-organized network of nanopores have ultra-high surface area and nanometer grain structure, therefore enabling high sensitivity. The sensors are described as robust and stable in harsh environments, and may be used for both chemical gas and physical (humidity, temperature) sensors and sensor arrays. U.S. Pat. No. 4,631,952 discloses a method of preparing a sensor by the formation of a dispersion of conducting particles within a polymeric material capable of swelling in the presence of the liquid, gas or vapor to be sensed; however, the sensors do not appear to be able to measure temperature, pressure, or anything but the presence or absence of the liquid, gas or vapor to be sensed, based on increasing resistivity as the particles are separated as the polymer swells. Disclosed particle sizes range from about 0.001 to about 10 microns (1 nanometer to about 10,000 nanometers). Examples of conductive particles are gold, platinum, silver, copper, nickel, stainless steel, ferrite, electrically conductive carbon black, and the like. U.S. Pat. No. 5,387,462 teaches a method of making a sensor for gas, vapor, and liquid from a composite article with an electrically conductive surface having an array of whisker-like microstructures with an aspect ratio of 3:1 to 100:1. U.S. Pat. No. 5,345,213 teaches a method for fabrication of temperature-controlled micromachined arrays for chemical sensor fabrication and operation. U.S. Pat. No. 6,079,873 describes a micro-hotplate-based differential calorimeter for detecting gases and chemical reactions. Although these prior methods provide improved methods for producing sensors and for detection of a particular gas and/or liquid, there is no disclosure of swellable polymeric materials comprising nanoscale sensors able to detect important downhole parameters, such as temperature and pressure. So far as is known, oilfield apparatus comprising nanosensors dispersed in a swellable elastomer have not been reported, nor their use in oilfield applications.
Common to all oilfield uses of swellable elastomers is exposure to hostile environments, such as hostile organic and inorganic chemicals, temperatures, pressures and mechanical subterranean environments that tend to unacceptably decrease the life and reliability of the swellable elastomers. There remains a need in the natural resources exploration, production, and testing field for improved data gathering capabilities to monitor and/or ascertain temperature, pressure, viscosity, pH and other data about the wellbore environment in the vicinity of a swellable elastomer.